This invention relates to polyetherimides. More particularly, it relates to polyetherimides having extremely good resistance to high temperatures.
Polyetherimides are well known commercially available polymers having advantageous properties including thermal oxidative resistance, good mechanical strength, excellent electrical properties and good chemical resistance. Commercially available polyetherimides include those of the type which may be prepared by the reaction of such aromatic amines as m- and p-phenylenediamine with bis(ether anhydrides) such as 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, hereinafter sometimes designated "BPADA" for brevity. Their temperature stability is high, as shown by a glass transition temperature in the range of 215-220.degree. C.
It is of interest, however, to prepare polyetherimides having still better resistance to high temperatures. Glass transition temperatures above 250.degree. C. would be especially desirable.